Durability of standard concrete incorporating

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Durability of standard concrete incorporating

  1. 1. INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME TECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 3, Issue 2, July- December (2012), pp. 373-379 IJCIET© IAEME: www.iaeme.com/ijciet.aspJournal Impact Factor (2012): 3.1861 (Calculated by GISI) © IAEMEwww.jifactor.com DURABILITY OF STANDARD CONCRETE INCORPORATING SUPPLEMENTARY CEMENTING MATERIALS USING RAPID CHLORIDE PERMEABILITY TEST M. Vijaya Sekhar Reddy1*, Dr.I.V. Ramana Reddy2, N.Krishna Murthy3 1 *HOD and Assistant Professor, Department of Civil Engineering , Srikalahasteeswara Institute of Technology, Srikalahasti, and Research Scholar at Sri Venkateswara University College of Engineering, Tirupati, Andhra Pradesh, India, Email Id: skitce.hod@gmail.com 2 Professor, Department of Civil Engineering, Sri Venkateswara University College of Engineering, Tirupati, Andhra Pradesh, India, Email Id: svshaar4@yahoo.co.in 3 Assistant Engineer, YVU, Kadapa and Research Scholar at Sri Venkateswara University College of Engineering, Tirupati, Andhra Pradesh, India, Email Id: krishpurna@yahoo.in ABSTRACT Concrete has today very demanding performance requirements. The concrete durability crisis which started to attract public attention forced the engineers to think about the performance of concrete proper mix design and careful construction using the best available materials and technologies are necessary to achieve quality concrete structures. The February 2007 report issued by the International Panel on Climate Change (IPCC) has started in no uncertain terms that global warming is no longer an issue that has to be debated. According to the report, global warming is here, and drastic actions are needed for the long term sustainability of our environment. It is in this context that this paper discusses the role of supplementing cementing materials as partial replacement for cement in concrete in reducing green house gas emissions. In the last decade the use of Supplementary Cementing Materials (SCM) has become an integral part of high strength and high performance concrete mix design. The addition of SCM to concrete reduces the heat of hydration and extends the service life in structures by improving both long term durability and strength. One of the important changes is the introduction of micro technology for concrete with ultrafine and various other micro sized and fine cementitious materials. It is now possible to achieve excellent particle packing and thereby comply with the demands for performance in concrete both in fresh and in the hardened state. Some of the commonly used SCMs are Flyash, Silica fume, Blast furnace slag & Metakaoline. This paper presents the results of the durability characteristic properties of M40 grade of concrete with Super Plasticizer. The durability was evaluated using Rapid Chloride Permeability Test. KEYWORDS: Standard Concrete, Supplementary Cementing Materials (SCMs), Superplasticizer, Durability, Rapid Chloride Permeability Test. 373
  2. 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMEINTRODUCTION Durability of concrete plays an important role in the service life of RCC structures. Itcan be enhanced by improving impermeability, resistance to chloride ion diffusion andabrasion resistance. One of the ways to achieving this is by adding super plasticizers andsupplementary cementing materials. Many researchers have demonstrated the beneficial effects of using GroundGranulated Blast Furnace Slag (GGBS) and flyash as Cement Replacement Materials andobtained a reduction in the rate of penetration of chloride ions concrete reducing the potentialof chloride induced corrosion [1]. Smith Kevin et al., have established a testing regime to optimize the strengths anddurability characteristics of a wide range of high-performance concrete mixes. One of theprime methods of optimizing the mixtures was to implement supplemental cementitiousmaterials, at their most advantageous levels. Fly ash, Slag cement, and Micro silica all provedto be highly effective in creating more durable concrete design mixtures. These materialshave also shown success in substantially lowering chloride ingress, thus extending theinitiation phase of corrosion [2]. Swamy, (1996), defines that a high performance concrete element is that which isdesigned to give optimized performance characteristics for a given set of load, usage andexposure conditions, consistent with requirement of cost, service life and durability [3]. One of the main reasons for deterioration of concrete in the past is that too muchemphasis is placed on concrete compressive strength rather than on the performance criteria.The deterioration of reinforced concrete structures usually involves the transport ofaggressive substances from the surrounding environment followed by physical and chemicalactions in its internal structure. The transport of aggressive gases and/or liquids into concretedepends on its permeation characteristics. As the permeation of concrete decreases itsdurability performance, in terms of physio-chemical degradation, increases. Therefore,permeation of concrete is one of the most critical parameters in the determination of concretedurability in aggressive environments [4]. High performance concrete (HPC) is that which is designed to give optimizedperformance characteristics for the given set of materials, usage and exposure conditions,consistent with requirement of cost, service life and durability. The Ordinary PortlandCement is one of the main ingredients used for the production of concrete and has noalternative in the construction industry. Unfortunately, production OPC involves emission oflarge amounts of Carbon dioxide (CO2) gas into the atmosphere, a major contributor forGreen House Effect and Global Warming. Hence it is inevitable either to search for anothermaterial or partly replace it by SCM which should lead to global sustainable development andlowest possible environmental impact. Another advantage of using SCMs is increase indurability of concrete which consequently results increase in resource use efficiency ofingredients of concrete which are depleting at very fast rate. Long term performance ofstructure has become vital to the economies of all nations [5]. Durability of concrete is the ability of concrete to remain fully functional over anextended period under prevailing service conditions for the purpose for which it has been 374
  3. 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMEdesigned. The durability of concrete is classily related to its permeability. The permeabilitydictates the rate at which aggressive agents can penetrate to attack the concrete and the steelreinforcement. Corrosion related damage to the concrete structure is a major problemassociated with high cost of repairs; sometimes replacement of structure. HPC is the key toachieve impermeable, durable and improved protection of embedded steel [6].MATERIALS USED IN THE PRESENT STUDYCement Ordinary Portland cement Zuari-53 grade conforming to IS: 12269-1987 [6] wereused in concrete. The physical properties of the cement are listed in Table 1. Table 1. Physical Properties of Zuari-53 Grade Cement Sl. No. 1 2 3 4 5 Initial Final Specific Normal Compressive strengthProperties setting setting gravity consistency (Mpa) time time 3 days 7 days 28days Values 3.15 32% 60 min 320 min 29.4 44.8 56.5Aggregates A crushed granite rock with a maximum size of 20mm and 12mm with specificgravity of 2.60 was used as a coarse aggregate. Natural sand from Swarnamukhi River inSrikalahasthi with specific gravity of 2.60 was used as fine aggregate conforming to zone- IIof IS 383-1970 [7]. The individual aggregates were blended to get the desired combinedgrading.Water Potable water was used for mixing and curing of concrete cubes.SUPPLEMENTARY CEMENTING MATERIALSFlyash Fly ash was obtained directly from the M/s Ennore Thermal Power Station,Tamilnadu, India. The physicochemical analysis of sample was presented in Table 2. Table 2 . Physicochemical properties of Flyash sample. Sample Specific Specific Moisture Wet Turbidity pH Gravity Surface area Content density (NTU) (m2/g) (%) (gram/cc) 2.20 1.24 0.20 1.75 459 7.3 Flyash Chemical Composition, Elements (weight %) SiO2 Al2O3 Fe2O3 CaO K2O TiO2 Na2O3 MgO 56.77 31.83 2.82 0.78 1.96 2.77 0.68 2.39 375
  4. 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMESilica Fume The silica fume used in the experimentation was obtained from Elkem Laboratory,Navi Mumbai. The chemical composition of Silica Fume is shown in Table 3. Table 3. Chemical composition of Silica Fume. Iron Calcium Magnesiu Chemical Silica Alumina Alkalies as Oxide Oxide mComposition (SiO2) (Al2O3) (Na2O+K2O) (Fe2O3) (CaO) Oxide (MgO)Percentage 89.00 0.50 2.50 1.20 0.50 0.60Metakaoline The Metakaoline was obtained from M/s. 20 Microns Limited, Baroda, India. Thechemical composition of Metakaoline is shown in Table 4. Table 4. Chemical composition of Metakaoline Chemical SiO2 Al2O3 Fe2O3 TiO2 CaO MgO SO3 Na2O K2O LOIComposition Mass 52 42 to < 1 to Percentage to <3 0.1 < 0.1 <0.1 < 0.05 <0.4 <1 44 1.4 (%) 54Super Plasticizer VARAPLAST SP123 is a chloride free, Superplasticising admixture based onselected synthetic polymers. It is supplied as a brown solution which is instantly dispersiblein water and also it can provide very high level of water reduction and hence major increasein strength can be obtained coupled with good retention of workability to aid placement.RESULTS AND DISCUSSIONS In the present work, proportions for high performance concrete mix design of M40were carried out according to IS: 10262-2009 [8] recommendations. The mix proportions arepresented in Table 6 and Table 7. Table 6. Mix Proportion for M40 Concrete. Coarse aggregate Secondary Fine Super- Cement (20mm 20% & Water Cementing aggregate plasticizer 12.5mm 80%) Materials Composition 270 862 1097 140 115 7.7 in Kg/݉ଷ Ratio in % 1 3.193 4.062 0.518 0.425 0.0285The standards cylindrical disc specimens of size 100 mm diameter and 50 mm thick after 90days water curing were used in this test. As per ASTMC 1202-1997 [9]. The test results ofM40 mix of Binary system of concrete were compared with and without SCMs. 376
  5. 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMERAPID CHLORIDE PERMEABILITY TEST The rapid chloride permeability test for different concrete mixtures was carried out asper ASTM C1202 [9]. Standard cylindrical disc specimens of size 100mm diameter and50mm thick after 90days water curing were used. This test method covers the determinationof the electrical conductance of concrete to provide a rapid indication of its resistance topenetration of chloride ions. The apparatus consists of variable D.C. power supply which feeds constant stabilizedvoltage to the cells. The cells are made up of polymethyl methacrylate. The concretespecimens are kept in between the cells. The cells are connected to main instrument through 3pin plug and socket for voltage feeding. The charge of current flowing through the specimenis measured by using an accurate digital current meter. The cells have grooved recess on oneface and closed at other end. The specimen can be fit into the open faces of the cells. One ofthe cells is filled with sodium chloride (NaCl) solution 2.4M concentration and the other isfilled with 0.3M Sodium hydroxide (NaOH-0.3M) solution. The cylindrical disc specimen are coated with quick setting epoxy on their curvedfaces and mounted in the open spaces of the two cells. After checking the leak proofness, a60V potential difference is applied between the electrodes. The electrochemical cell in theassembly results in migration of the chloride ions from sodium hydroxide solution through thepores of the concrete specimen. The current passed was noted at every 30 minutes over aperiod of 6 hours and the total electric charge passed through the specimen is calculated usingthe expression. The Table 8 shows the rating of chloride permeability according to ASTMC1202-1997[9].The following formula, based on the trapezoidal rule can be used to calculate the averagecurrent flowing through one cell. Total Charge Passed in Coulomb’s (Qc) Q = 900(I0+2I30+2I60+2I90+2I120+…+2I300+2I330+I360) Where, Q = current flowing through one cell (coulombs) I0 = Current reading in amperes immediately after voltage is applied, and It = Current reading in amperes at t minutes after voltage is applied Table 8. Rating of chloride permeability Charge passing in coulombs Chloride permeability rating Greater than 4000 High 2001 to 4000 Moderate 1001 to 2000 low 100 to 1000 Very low Less than 100 NegligibleThe object of the test was to evaluate the durability performance of M40 mix and comparedwith conventional concrete. The Rapid Chloride Permeability test result of M40 is representedin Table 9 and corresponding graphical picture is shown in Figure 1 respectively. 377
  6. 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEME Table 9: Rapid Chloride Permeability Test Results of M40 Mix RCPT ( TOTAL CHARGE PASSED Sl. Percentage GRADE THROUGH IN No Replacement of SCMs COLUMBS @90 DAYS ) CONVENTIONAL 1 1850 CONCRETE 2 M40 20% FLYASH 1275 3 10% SILICA FUME 1245 4 10% METAKAOLIN 1290 RCPT ( TOTAL CHARGE PASSED THROUGH IN COLUMBS @90 DAYS ) 2000 1800 RCPT ( TOTAL CHARGE PASSED 1600 THROUGH IN COLUMBS 1400 @90 DAYS 1200 1000 800 600 400 200 0 ONLY CEMENT WITH 20% FLYASH WITH 10% SILICA WITH 10% FUME METAKAOLIN Fig 9. Rapid Chloride Permeability test results of M40 mixCONCLUSIONS1. In M40 grade of concrete as the water-cement ratios of 0.518 is insufficient to provide the good workability, hence super plasticizer is necessary for M40 mix.2. Rapid Chloride Permeability test results reveals that the total charge passed in Coulomb’s is low for M40 grade of concrete with replacement of 10% Silica Fume. But the total charge passed in Coulomb’s for conventional concrete is slightly higher than the concrete replaced with SCMs.3. The addition of SCMs causes pozzolanic reaction and thus resulting in improvement of pore structure of concrete leading to lower permeability, causing higher resistance to chloride ion penetration at the higher percentage replacement compared to conventional concrete. 378
  7. 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print),ISSN 0976 – 6316(Online) Volume 3, Issue 2, July- December (2012), © IAEMEREFERENCES[1] Bhaskar .S, Ravindra Gettu, Bharatkumar. B.H and Neelamegam. M, (2012) “Strength, bond and durability related properties of concretes with mineral admixtures”, Indian Concrete Journal, Vol. 86(2), pp. 9-16,.[2] Smith Kevin.M, Schokker Andrea. J, and Tikalsky Paul. J,( 2004) “Performance of supplementary cementitious materials in concrete resistivity and corrosion monitoring evaluations”, ACI Materials Journal, Vol.101(5), pp.385-390.[3] Swamy.R.N (1996) “High Performance Durability Through Design. International Workshop on High Performance Concrete”, ACI-SP, Vol.159 (14), pp. 209-230,.[4] Vaishali Ghorpade and Sudarsana Rao. H, (2011) “Chloride Ion Permeability Studies of Metakaoline based, High Performance Concrete”, International Journal of Engineering Science and Technology (IJEST), Vol.3 (2), pp.1617-1623,.[5] Khadiraranaikar. R.B, Chandrabansi .G.B. and Md. Asif Maruf,(2012) “Durability of High Performance Concrete Congaing Rice Husk Ash using Rapid Chloride Penetration Test, In Proceedings of International conference on Sustainability Challenges and advances in concrete technology (SCACT)”, Organized by Dept of Civil Engg , PSG College of Technology, Coimbatore, India,.[6] IS: 12269-1987, Specification for 53 Grade Ordinary Portland Cement, Bureau of Indian Standards, New Delhi, India, 1989.[7] IS: 383-1970: specifications for coarse and fine aggregates for natural sources of concrete, Bureau of Indian standards, New Delhi.[8] IS: 10262-2009: Concrete Mix Proportioning-guidelines, Bureau of Indian Standards, New Delhi.[9] Standard test method for electrical indication of concrete’s ability to resist chloride ion penetration, ASTMC 1202-97, Annual book of ASTM standards, vol.04.02,pp.639-644. 379

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